The invention relates to a decanter centrifuge with a rotating bowl provided with at least one solids discharge port and at least one clarified liquid discharge port and a screw conveyor disposed coaxially within said rotating bowl so as to be included in said rotating bowl rotated in the same direction with a differential rotational speed, where a feed suspension to be separated is introduced into a ring shaped space formed between said rotating bowl and said screw conveyor through a central feed pipe fixed to the end of the screw conveyor and supported in at least one bearing and can be separated by centrifugal force into a solid and a liquid phase so that said solid phase is discharged from said solid discharge port and said liquid phase is discharged from said clarified liquid discharging apparatus, whereby a liquid phase conduit is arranged in the shaft guiding the liquid phase outside of the bearings, a liquid phase valve provided outside the bearing on the side facing away from the bowl and screw.
A decanter centrifuge in the state of the art is shown in EP 0 447 742 A2 where the solid discharge port is arranged at the inside of the feed pipe end bearing. The liquid discharge port for the clarified liquid is on the side of the end plate connected to the drive shaft of the bowl and is equipped with a weir, which can be adjusted in its height by an adjusting weir board.
As the drive shaft has to have a certain diameter, usually in the range of the screw shaft, the liquid outlet can only be a great distance away from the axis. This leads to high energy consumption. Also JP 2002 336735 shows a decanter centrifuge with a rotating bowl and rotating screw with a liquid phase conduit arranged in the shaft with a discharge valve.